A solution of diisopropyldiazodicarboxylate (0.710 g, 3.50 mmol) in tetrahydrofuran (6 mL) was added dropwise to a mixture of 1-[(2,2-dimethyl-1,3-dioxolan-4-yl)methyl]-2-(ethoxymethyl)-1H-imidazo[4,5-c]quinolin-7-ol (prepared as described in Parts A-D of Example 372, 1.00 g, 2.80 mmol), tert-butyl 4-hydroxypiperidine-1-carboxylate (0.70 g, 3.50 mmol), and triphenylphosphine (0.920 g, 3.50 mmol) in tetrahydrofuran (35 mL) at 0° C. The resulting solution was allowed to warm to room temperature over 16 hours. The solution was concentrated under reduced pressure. The crude product was purified by chromatography (silica gel, gradient elution with 0-50% CMA in chloroform) to provide 1.16 g of tert-butyl 4-{[1-[(2,2-dimethyl-1,3-dioxolan-4-yl)methyl]-2-(ethoxymethyl)-1H-imidazo[4,5-c]quinolin-7-yl]oxy}piperidine-1-carboxylate as a white foam.
